textproduct: Albany

WHAT HAS CHANGED

Winter Weather Advisory issued for eastern Catskills (western Ulster/western Greene County) for late this morning through tonight, as overall snowfall accumulations have increased in this area.

KEY MESSAGES

1) Clipper system brings moderate to locally heavy snowfall across portions of SW Adirondacks and southern Green Mountains this afternoon into early Saturday afternoon. Strong gusty winds also expected associated with, and behind this clipper system, especially late tonight into Saturday.

2) Storm system approaching from the west could bring another round of strong winds and locally heavy rainfall Sunday night through Monday night.

3) Below normal temperatures return in the wake of the early week storm system and continues through late next week.

DISCUSSION

KEY MESSAGE 1... Strong clipper system currently across the Great Lakes region will gradually weaken as it approaches from the west later today and tonight. A surge of mid level warm advection will result in increasing clouds later this morning, with precipitation expanding eastward into the region this afternoon. For higher elevations, precipitation should be mainly snow, while in valley areas, precipitation may briefly start as rain or a rain/snow mix before changing to a brief burst of snow.

The main surge of warm advective precipitation should lift north and east of the region around or shortly after sunset, however persistent upslope processes will allow periods of light to moderate snow to continue overnight across the SW Adirondacks and higher terrain in southern VT. Then, as the system's cold/occluded front tracks eastward overnight, some convective snow/rain showers in valleys and snow across higher terrain will occur. Snow showers may linger into Saturday morning, before decreasing in coverage from SW to NE Saturday afternoon.

Overall total snowfall accumulations should range as high as 5-11 inches across higher terrain of the SW Adirondacks where the Winter Storm Warning is in effect. Surrounding this area, 3-7 inches of snow are expected across the Advisory areas in the SW Adirondacks, as well as portions of the eastern Catskills and higher terrain areas of southern VT. In valley areas, most accumulations should remain under an inch, and mainly on colder ground surfaces. However, during any brief bursts of heavier snow, some slushy accumulations could even occur on road surfaces this afternoon and evening.

In addition to the snow, strong winds are expected with this clipper system. Initially, gusty south to southeast winds are expected late this afternoon/evening, especially within north/south oriented valleys including near the Capital Region and portions of the Taconics and western New England, where gusts of 30-40 mph may occur. Then, behind the system amid sharp pressure rises, cold advection and deeper mixing, wind gusts of at least 35-45 mph are expected Saturday, with some potential for gusts reaching 50-55 mph especially within typically favored channeled W/NW flow regime areas such as the Mohawk Valley, Capital Region and Berkshires, as 01Z/Fri NBM 24-hour probs for peak gusts >50 mph are 20-55% in these areas. Wind Advisories will likely be issued for at least some of these areas later today.

KEY MESSAGE 2...

Next system develops across the Plains and tracks into the Great Lakes region Sunday into Monday, with a strong cold front associated with this system approaching our region Monday afternoon or night. A warm front may bring a brief period light snow or mixed precipitation Sunday, especially areas north of I-90. Warmer air will eventually build into the region from the south and west Sunday night into Monday ahead of the approaching cold front.

Strong moisture transport and anomalously high PWAT's (LREF indicates PWATs within 99th percentile of Climo) ahead of front suggest moderate to locally heavy rain Monday and/or Monday night. There are even some hints at some instability allowing for embedded thunderstorms, with 01Z/Fri NBM suggesting probs for >250 J/kg CAPE within the Hudson River Valley extending into portions of NW CT. 01Z/Fri NBM 24-hour probs for >1" ending 8 AM Tuesday are 40-65%, greatest across the mid Hudson Valley, NW CT and Berkshires. This moderate-heavy rainfall will increase chances for additional hydrological concerns given already high water levels across portions of the region from recent snowmelt and rainfall, particularly across the Housatonic basin and across the Upper Hudson River/Mohawk River basin, southern Adirondacks and southern VT where MMEFS suggests chances for at least a few points to reach minor flood stage once again late Monday into Wednesday.

LREF joint probs of MU CAPE >500 J/kg and 0-500 mb bulk wind shear >30 KT are 20-40% across portions of the mid Hudson Valley, NW CT and Berkshires Monday afternoon/evening, so we can not complete rule out some isolated severe thunderstorms with or just ahead of the cold front as well.

Strong south winds will be possible ahead of the front Monday and Monday evening, and again in the wake of the front for next Tuesday. 01Z/Fri NBM indicates 24-hour probs ending 2 AM Tuesday for max wind gusts >50 mph at 40-60% across portions of the Taconics and Berkshires, mainly for the southerly winds ahead of the front.

KEY MESSAGE 3...

The cold front moves east of the region Monday night or early Tuesday morning, with some possibility for a period of snow or mixed precipitation in the wake of the front especially areas west of the Hudson River. Much colder air with below normal temps return Tuesday into Wednesday, with slow moderation by Thursday. Daytime high temps mainly in the 20s and lower/mid 30s Tuesday-Wednesday, eventually reaching the 30s/40s by Thursday/Friday. Outside of some possibly lake effect snow showers, mainly dry weather is expected until next Friday when a clipper system could bring additional light snow or rain portions of the region.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

Through 06z Saturday...VFR conditions at all terminals as of 1:20 AM EDT. Mainly VFR conditions expected through early this afternoon with SCT to BKN mid and high clouds around. Have also included VCSH for the next several hours at ALB/PSF due to lake effect snow showers, but if any of these snow showers move over one of the terminals they should be brief.

This afternoon, a clipper system will bring snow/snow showers to the region. Have adjusted the timing forward an hour or so from the previous TAFs. IFR vsbys and MVFR to IFR cigs expected within snow showers, with the highest confidence at GFL. Less coverage of snow showers expected at the other terminals, especially POU. Could also see some rain mix in at POU as well. There may be a brief lull in snow/snow shower activity tomorrow late afternoon or evening at ALB/POU/PSF, but additional snow showers fill back in for the last few to several hours of the TAF period.

Winds tonight will be light and variable at GFL, but at from the west at 5-10 kt at ALB/POU/PSF with gusts to around 20-25 kt at ALB/PSF. Winds diminish towards sunrise at all terminals, then switch to the S/SE by late morning. Winds then increase to around 10 kt with gusts to 20-25 kt from the S/SE (strongest in the afternoon at ALB/PSF) through the end of the TAF period. Borderline LLWS criteria this afternoon into tonight at all terminals with a 40 kt southerly low-level jet overhead, but have not included in the TAFs at this time due to the relatively strong sfc winds.

Outlook...

Saturday Night: Low Operational Impact. Breezy. NO SIG WX. Sunday: Moderate Operational Impact. Breezy. Chance of SN. Sunday Night: High Operational Impact. Breezy. Likely RA. Monday: High Operational Impact. Windy With Gusts To 31 kts. Definite RA...TSRA. Monday Night: High Operational Impact. Very Windy With Gusts To 43 kts. Definite RA...SN. Tuesday: Moderate Operational Impact. Windy With Gusts To 32 kts. Slight Chance of RA...SN.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...Winter Storm Warning from 11 AM this morning to 2 PM EDT Saturday for NYZ032-033. Winter Weather Advisory from 11 AM this morning to 2 PM EDT Saturday for NYZ042-082. Winter Weather Advisory from 11 AM this morning to 8 AM EDT Saturday for NYZ058-063. MA...None. VT...Winter Weather Advisory from 11 AM this morning to 2 PM EDT Saturday for VTZ013-014.